Two famous double stars with the Sightron inifini D50 refractor

 The inifini D50 refractor is a 50-mm aperture, 540-mm focal length (f/10.8) achromatic refractor manufactured by Sightron Japan.  It was designed primarily as a visual instrument, but it is of course fun to see how it performs photographically as well.

Polaris (Alpha Ursae Minoris) is well known as the "North Star", but it has other qualities which are of interest to astronomy enthusiasts.   It is the closest Cepheid Variable, which makes it an important part of the cosmic distance ladder.  It is also a triple-star system.  Two of the components are visible with modest amateur telescopes.  The third component is a close companion of the massive primary star and has only been resolved with the Hubble Space Telescope.

 

Polaris.  Sony A7iii + Rokinon 75mm f/1.8 + Hoya Softon filter.

Polaris B is a magnitude-8.7 companion separated from Polaris A (mag 2) by 18 arcsec.  To photograph this star with the D50, an Astro-Tech 2x telecentric focal extender was used with an Olympus E-M5iii camera.   The camera and extender was inserted directly into a Baader 90-deg Amici prism diagonal.  The telescope was mounted on a manual alt-az mount.  Polaris is close enough (0.62°) to the north celestial pole that a tracking mount is not required for short exposures.

Sightron infini D50 + Baader prism and camera.

 

Polaris A and B with the infini D50 refractor. 2-sec exposure.

 Mizar and Alcor is a well known naked-eye double star in the handle of the Big Dipper. What is less well known is that this is actually a six-star system.  Mizar, the brightest component of the pair, is easily resolvable in small telescopes into two components, each of which is also a spectroscopic double star.  Alcor, the fainter companion to Mizar, is a spectroscopic double as well.

Mizar and Alcor (center). Rokinon 75mm f/1.8 + softon filter.

 The Mizar and Alcor system was photographed with the D50 refractor mounted on a ZWO AM3 tracking mount.

Mizar (top) and Alcor (bottom). 2-sec exposure.

 

 

Lunar eclipse

The full moon of March is traditionally known as the "Worm Moon".  This year it was also eclipsed.

 The sequence below spanned the time from 2:52 am to 4:46 am MST in the wee hours of 03 March.  There was a cloud band to the north at the start and some clouds did eventually come sliding past, but the eclipse was mostly unobstructed.  I gave up just before the official end of totality because a stubborn cloud was partially obscuring the moon.

The copper hue captured so well by the camera was not very apparent visually.  Even when viewed through the Sightron D50 refractor at 22x, the color was very washed out.  There may have been a high thin cloud layer attenuating the color.  A hint of this haze layer is evident in the middle picture of the montage below.

Equipment used: Astro-Tech AT72EDII refractor + Olympus E-M5iii camera on a ZWO AM3 mount.

Maximum eclipse: 04:34 am

 

Just past peak, with background stars visible (north to the right)

Some favorites from 2025

 I was recently looking for some general-interest photos from last year and came up with this short list.  There is only one Milky Way photo in the set, and its the winter Milky Way, not the more impressive summer version.

Northern Lights over Creede, 11 Nov. Laowa 15mm f/2.

 

Venus, Jupiter, and Orion rising over Snowshoe Mountain, 02 Sep. Leica 9mm f/1.7.

Venus is immersed in the soft glow of Zodiacal Light just above the mountain ridgeline.

Jupiter, Orion, and Sirius over Snowshoe Mt, 02 Sep. Olympus 17mm f/1.8.

Sirius is the brightest star in the night sky, but in the two photos above it is outshone by the planets Jupiter and Venus.  The reddish hue of the supergiant star Betelgeuse also stands out nicely in the second photo.

Comet C/2025 A6 (Lemmon) setting behind Bristol Head, 29 Oct. Canon FD 300mm f/4L.

The Winter Milky Way, 02 Nov. Leica 9mm f/1.7

In this photo the winter Milky Way arcs above the green airglow along the southern horizon.  There is a beam of blue light projecting upward from the bottom right.  This comes from an inconsiderate landowner two miles away on Highway 149.  I was initially annoyed by this light trespass (and still am), but it does add an unusual element to the picture.

February Moon, March Sun

 Last night (28 Feb) the Sightron infini D50 f/10.8 refractor was used to photograph the 12.4-day moon.  There were some thin cloud bands passing, but there was enough time to catch a clear shot.  The camera used on the moon was the Olympus E-M5iii.

This morning (01 Mar), the D50 was used with a ZWO ASI294MC-Pro camera to photograph the sun.  In addition to a front-mounted Baader solar filter,  ND-0.9 and UV-IR-cut filters were also used.  

Both of these shots were meant to test a new mounting arrangement for the D50 refractor.  This scope ships with a 4-inch flush-mounted  Vixen dovetail that works fine with the light-weight stock diagonal and eyepieces.  However, when heavier accessories are attached, such as a camera or large eyepiece, balance becomes tricky because there is not enough forward movement available. The new arrangement consists of two More Blue 60-mm tube rings (from Astro Hutech)  and PrimaLuceLab dual-sided Vixen-Arca-Swiss dovetails.

 

Sunspots are visible again after a stretch of several spotless days.

Moon photography setup.

 

Solar photography setup.

The Moon at 5.7 days

 There were some thin clouds in the early-evening western sky, but they didn't prevent getting a shot of the 5.7-d moon.  The telescope used was the Sightron Japan infini D50, a 50-mm aperture, 540-mm focal length achromat.   This scope seems to perform quite well.  There is only a hint of chromatic aberration along the limb of the moon in the digital image.  Visually, a Nagler T6 5-mm eyepiece was used to provide a 108x view of Jupiter.  The cloud bands were very well defined.

 

Spotless Sun

 There are currently no sunspots visible on the face of the sun.  It is blank.

 This image was taken with a Sightron Infini D50 refractor (50mm, f/10.8) and a front-mounted solar filter.

infini D50

 Compare the spotless image above to the sun two weeks ago on 7 February, when a large active sunspot group was traversing the face:

7 February, AT72EDII refractor.

 Sunspots may be absent, but the sun is far from quiet.  Many large prominences are visible around the rim in hydrogen-alpha light.

Today, 22 Feb. Hydrogen-alpha sun.  Lunt LS50THa double-stacked.

 

false-color image.

The Moon at 4.7 days

 Tonight  (Saturday) the Moon is 4.7 days past new.  This image was taken with an Orion 80mm ED f/7.5 refractor and Olympus E-M5iii camera.  The large circular feature near the middle on the terminator is Mare Nectaris.